Clock Frequencies

The following chart shows how well the processor sustains its clock frequency and which boost clock speeds are achieved at various thread counts. This test uses a custom-coded application that mimics real-life performance—it is not a stress test like Prime95. Modern processors change their clocking behavior depending on the type of load, which is why we provide three plots with classic floating point math, SSE SIMD code, and modern AVX vector instructions. Each of the three test runs calculates the same result using the same algorithm, just with a different CPU instruction set.

Overclocking

Overclocking the Ryzen 9 9900X is pretty easy, thanks to the unlocked multiplier.

For manual all-core overclocking, I initially set the voltage to 1.35 V. Cooling was surprisingly manageable, likely due to the dual CCD design that distributes heat over a larger surface area than single CCD models. Although I managed to boot at an impressive 5.5 GHz, the system crashed quickly, even at a higher voltage of 1.4 V, especially during heavy application usage. A clock of 5.4 GHz was stable in most scenarios, but a few applications still caused issues, so I settled for 5.3 GHz. At this frequency, I was able to reduce the voltage to 1.3 V, which improved energy efficiency, too.

Even at 5.3 GHz, the all-core overclock can't match the performance of the "PBO Max" configuration, which achieves better results by reaching higher clock speeds than 5.3 GHz. However, in other workloads like rendering, the 5.3 GHz all-core overclock ends up with higher clocks because PBO takes a more cautious approach in those scenarios.

Overclocking using PBO/Curve Optimizer works exactly the same as before. There's a new feature called Curve Shaper, which lets you adjust the Curve Optimizer voltage dynamically based on frequency and temperature. We will have a longer article on this in the future. At this time changing Curve Shaper values is done manually by entering numbers. BIOS vendors are working on implementing GUI-based controls for this, AMD will also add an easy-to-use interface to Ryzen Master.

• Maximum FCLK is between 2100 and 2200 MHz, so no significant changes from Zen 4.
• Same with memory, which tops out around 6400 MHz unless you're engaging a 2:1 divider, which will likely have mixed performance results.
• The thermal target/limit is still 95°C, and can't be raised, same as before. When manual overclocking (= all-core multiplier) is enabled, the temperature limit is 115°C, same as before.